34. Membrane Elevation of Sea-urchin Egg by Intracellular Injection

抄録

Injection of various solutions into the unfertilized egg of a seaurchin, Strongylocentrotus pulcherrimus, shows that the membrane elevation occurs when the concentration of intracellular free Ca-ions is suddenly reduced. In a medium relatively poor in Ca-ions, mechanical stimulation due to insertion of the micropipette seems to induce the diminution of intracellular free Ca-ions, probably by an enhanced ionic exchange across the cell membrane. A prolonged subjection of the egg to Ca-free media makes the cell insensitive to the stimulation for membrane elevation, but this change is reversible.
A dialyzing membrane which covers the plasma membrane of theunfertilized egg, is demonstrated by injection of a colloidal solution in the interstice between these two membranes. A possibility is pointed out that the diminution of intracellular Ca-ions may initiate a chain of events which make the egg to secrete in the interstice some substance so as to increase greatly the degree of dispersion of colloidal aggregates already existing in the interstice and to induce a colloidosmotic swelling in the interstice. It is suggested that some parthenogenetic substance may act directly on the colloidal aggregates in the interstice, without entering the cell and hence without reducing the intracellular Ca-ion concentration.